Looks like you are flexing your knees at the top. Just extend your hips and lift your chest.
I wouldn't look up at the ceiling like you are doing. I know some people teach it that way, but Rip doesn't. Pick a spot on the floor about 12 feet away and look at it. It helps your balance. It looks like you are leading with your head.
1st rep: you jerk it off the floor and lose a bit of your back tightness. Think of squeezing it off the floor. Also, are you bouncing it off the floor on the subsequent reps?
They aren't terrible, but that's what I see.